Think of the early solar system like a wild game of bumper cars. Scientists believe it was chaotic, filled with planetesimals, asteroids, and comets crashing into each other. Recently, NASA’s Hubble Space Telescope captured similar collisions in a distant star system called Fomalhaut.
“I’ve never seen a light appear out of nowhere in an exoplanet system,” said Paul Kalas from UC Berkeley. “In past Hubble images, it wasn’t there. Now we see the aftermath of a huge collision and a cloud of dust unlike anything in our solar system.”
Fomalhaut, just 25 light-years from us, shines brightly in the constellation Piscis Austrinus, or Southern Fish. It’s much larger and brighter than our Sun, surrounded by rings of dust.
In 2008, Hubble found a potential planet in this system, named Fomalhaut b. However, it turns out this “planet” is actually a dust cloud caused by earlier collisions. During recent observations, researchers spotted another bright light nearby, dubbed “cs2.” This discovery is unusual because cs1 and cs2 are very close to each other, suggesting a pattern rather than randomness in these collisions.
Why are these two events happening in such a short time? Previous theories suggested that such collisions occur every 100,000 years. Yet, within just 20 years, we’ve seen two. Kalas explained, “Imagine watching a movie of the last 3,000 years sped up. You’d see a lot of flashes from collisions in Fomalhaut’s system.”
The collision between celestial bodies plays a crucial role in forming planetary systems, but they’re hard to observe. Mark Wyatt from the University of Cambridge noted, “This observation helps us estimate the size of the colliding bodies and reveal how many there might be.” He estimates that the colliding objects were about 37 miles wide, and suggests there could be around 300 million similar objects in Fomalhaut’s orbit.
This system serves as a natural lab to study the behavior of planetesimals during collisions, which gives insights into their composition and formation.
But these cloud-like formations pose challenges for future missions aiming to find real exoplanets. Kalas warned, “Fomalhaut cs2 looks just like an extrasolar planet reflecting starlight.” This means future observations might mistake such dust clouds for planets.
Over the next three years, Kalas and his team will continue monitoring cs2. They hope to discover if it fades or brightens. Being closer to the dust belt, cs2 might interact with more material, possibly leading to brighter displays.
They’ll also use the Near-Infrared Camera (NIRCam) on the James Webb Space Telescope, which can analyze the dust cloud’s composition and size. Hubble focuses mainly on visible light, while Webb specializes in infrared. This combined approach will deepen our understanding of the dynamic Fomalhaut system, opening doors for future studies.
This research appears in the December 18 issue of Science. For more insights, visit [Science](https://www.science.org/doi/10.1126/science.adu6266).
The Hubble Space Telescope, now over 30 years old, keeps making groundbreaking discoveries that expand our knowledge of the universe. It’s a collaborative project between NASA and the European Space Agency, managed by NASA’s Goddard Space Flight Center.
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Astrophysics, Astrophysics Division, Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Stars
